Polymeric materials

ABSTRACT

A process for the manufacture of cellular polyurethanes which comprises intimately mixing: A. A PREPOLYMER PREPARED BY THE REACTION OF A POLYESTER POLYOL WITH AN EXCESS OF A POLYISOCYANATE COMPRISING DIPHENYLMETHANE DIISOCYANATE, AND B. A MIXTURE CONTAINING A POLYETHER POLYOL, BLOWING AGENT, CATALYST AND SURFACE ACTIVE AGENT, THE RATIO OF ISOCYANATE GROUPS IN COMPONENT (A) TO ACTIVE HYDROGEN ATOMS IN COMPONENT (B) BEING SUBSTANTIALLY WITHIN THE RANGE OF 0.95:1 TO 1.2:1.

United States Patent 11 1 Allport et al.

1451 Aug. 26, 1975 POLYMERIC MATERIALS [75] lnventors: Dennis CharltonAllport; Graham Briggs, both of Manchester England [73] Assignee:Imperial Chemical Industries Limited, London, England 221 Filed: Jan.14,1974 21 Appl. No.:433,404

[30] Foreign Application Priority Data Jan. l9 i973 United Kingdom2738/73 [52] US. Cl. 264/51; 260/25 AM; 260/25 AN; 260/25 AZ; 260/25 BD;264/455 [51] Int. Cl. 8290 7/02; C080 18/10;

C080 1 C08G l8/66 [58] Field of Search... 260/25 AN, 2.5 AP, 2.5 AT,260/25 AZ, 2.5 BD, 2.5 AM; 264/5l, 45.5

[56] References Cited UNITED STATES PATENTS 3.186.971 H1965Hostcttlcr 1. 260/25 AN 359L532 7/l97l Ahcrcrombie 260/25 AN 359L5617/l97l Kazama 260/25 AN 3.66l,8ll 5/l972 Hardy 1 1 260/25 AN 3,666,7245/l972 Hostcttler 260/275 AN 3,674,721 7/l972 Aufdcrmarsh 1 260/25 AT3.851795 l2/l974 Jenkins .v 260/25 BD 3.856.7l6 12/l974 Jenkins .1260/25 AN Primary Examiner M. J. Welsh Assistant Exan1iner-C. Warren lvyAttorney, Agent, or FirmCushman. Darby & Cushman [57] ABSTRACT 1 Claim,No Drawings POLYMERIC MATERIALS This invention relates to polymericmaterials and more particularly to a process for the manufacture ofcellular polyurethanes.

According to the invention there is provided a process for themanufacture of cellular polyurethane which comprises intimately mixing:

a. a prepolymer prepared by the reaction ofa polyester polyol with anexcess of a polyisocyanate comprising diphenylmethane diisocyanate. and

h. a mixture containing a polyether polyol. blowing agent. catalyst andsurface active agent.

the ratio of isocyanate groups in component (a) to active hydrogen atomsin component (/1) being substaw tially within the range of (l.95:l tol.2:l.

The prepolymer. referred to above as component ((1) may be preparedusing the conditions that have been described in the prior art for suchpreparations. Thus. the polyisocyam te and the polyester polyol may bereacted togethe at normal or elevated temperatures. optionally in thepresence of a catalyst. until the reaction is subsuintially complete. ItIs generally preferred to lorm the p epo'ymer by reacting thepolyismyanate with the polyester polyol at a temperature within therange (if-120C. The polyisw'yanate is used in an excess amount relativeto the p lyes er polyol. that is t say the ratio ofisocyanate groups inthe polyisocyanate to active hydrogen atoms (present in hydroxyl andcarboxyl gr ups) in he polvester polyol is greater than ll): l.Preferably his ratio should be at least 4: I so that the viscosity ofthe prepolymcr is not excessively hi h. Suitab y. the prepolymer has anNCO content of lS-ZV/r.

The polyisocyanate used n preparing he prepolymer comprisesdiphenylmcthanc diisocya ate. Accord ngly. useful polyisocyanatesinclude pure 4.4- diphenvlrn-rthanc tli cyanate as well as m xtures ofthe latter is mer with the corresponding 2/ i: rncr. Mixtures of the 4.and 2. '-i.-'omcrs ontain g up to 10% of the Z.4-isomer are commerciallya ible. Also uselul are the so-called c ude diphchvi mtha r diisocyanatecomposition particularly thosi: c ntai ing from 30% to 90%. prefe ablyfrond-W1 to 80%. by weight of diphenylmcthane diisocyanates. theremaindcr being largely polymethylene polyphenyl polyisocyanates offunctionality greater than two. Such compositions may be obtained by thephosgenation olcrude diaminod]phenylmethanc as has been fully describedin the prior art.

Polyester polyols suitab fo e in preparing he prenolynier have bee fullnscri ed in the prior art relating to cellu a i "us. such polyesters maybe made from polycar 'im'ylic acids and polyhyd ic alcohols. Suitablepolyca' oxy ic acids include succinic. glutaric. ad pic. sc aphthalic.isophthallc. tcrephthalic and trim sir; 'C 'lS. Mixtures of acids may heused. Examples of'poivhydric alcohols include ethylene glycol. propyleneglycol. tetramcthylene glycol. dieth- \lcne glycol. decamcthyleneglycol. glycerol. trimethylolpropane and pcntacrythritol.

Particularly suitable polyester polyols for use in making theprepolymers have from 2 to 4 hydroxyl groups per molecule and hydroxylnumbers of from 2] to 2Z4 preferably from 30 to 120 and especially fromSt) to fill.

Component (/1) used in the process of the invention is a mixturecontaining a polyether polyol and any blowing agents. catalysts andsurface active agents requircd for the production of a cellularpolyurethane. If desired. the mixture may contain other conventionalingredients of polyurethane foam-forming reaction mixtures other than apolyisocyanate. Conveniently. the mixture contains all the ingredientsof the foamforming reaction mixture except the polyisocyanate andpolyester polyol. Examples of other ingredients which may be present inthe mixture include flameretardants. for example tris chloropropylphosphate. pigments. fillers and low molecular weight cross-linking orchainextending agents such as ethylene glycol. 1.4- butanediol. glyceroland phenylene diamine.

Polyether polyols which may be present in component (b) may be preparedby the reaction of one or more alkylene oxides with a compoundcontaining a plurality of active hydrogen atoms. Suitable alkyleneoxides include ethylene oxide. epichlorohydrin. l.2- propylene oxide.1.2-butylene oxide. 2.3-butylene oxide and styrene oxide. Mixtures oftwo or more oxides may be used if desired. for example mixtures ofethylene and propylene oxides. or. as a further variant. the activehylhogan-conta ning compound may be rea ed with two or more alkyleneoxides in successive s ges. for e amp e using propylene oxide in thefirst st ge and e hy ne o ide n th second or. conversely. ethylene oxidein th first stage and propylene oxide in the second Compounds containinga plurality of active hy gen a m it which the a kylene oxides may bereacted incl-uh; water. "lmm'W'llU. hydrazine. cyanuric acid.phosphorous. phosphoric or phosphonic acids. polyhydroxy compounds. forexample ethylene glycol, propylene glycol. diethylene glycol. glycerol.trimethylolpropane. 'rie hano arninc. pentaerythritol. tlOFhltUl.sucrose. pheaoliiirmaldchyde reaction products. resorcinol andphloroglucinol. aminoalco ols. for example monoethan ani ne and die h nine. palyamines. For example ethylene d v-nimh w nethylene dianiine.tolylem: diami 's and d nmim-r ipheny'methanes and polycar 'myl a ids.h" examp e ar'ipic acid. terephthalic aci a d trimesic a-"id. The c'idions for the reaction bet een the a ky ne oxide and the active hydrogencontaining (.UltpLHJllLl may be those fully described in the prior tusing. f r example. asic can" lysts su h as potassium hydroxide oracidic catalysts such as boron trifluo irle. The reaction pr'r uz s mayhave molecula w igh s of up to ll) (Ji l) ace rdi'1g to the "mount oalliylcne oxide reacted wi h "u. active hydrogen-containing compound.

Particularly su table polyether polyo s for use in the process of heinven on are polyoxypropyene and poly (oxypropvle ni-r-cxyethylene)polyols having rom two to four hydroxyl groups per molecule andhydroxyl numbers of from II to 224. preferably from 25 to 1 l2 andespecially from 30 to (ill.

Blowing agents which may be present in component lb] have been ullydescribed in polyurethane foam literature. They include water whichreacts with isocyanate groups in the prepolymer to form carbon dioxideand inert volatile liquid blowing agents. The latter blowing agentssuitably have boiling points not exceed ing ll)(l( at a mosphericpressure and preferably not exceeding 50C. Examples of such liquids arehalogenated hydrocarbons such as methylene chloride. vinylidenechloride. and particularly fluorinated hydrocarbons such astrichloromonolltuwromethane. dichlorodifluoromethane.monochlorodifluoromethane. d

chlorotetrafluoroethane and l. l ,2-triehloro-l .2 2- trifluoroethane.Mixtures of these low boiling-point liquids one with another and/or withother substituted or unsubstituted hydrocarbons may also be used. Theamount of blowing agent is selected in known manner to provide cellularpolyurethanes of the desired density under the particular foamingconditions being used.

Catalysts which may be used in the process of the invention have beenfully described in the prior art relating to polyurethanes and includetertiary amines and organic metal compounds, particularly tin compounds.Examples of suitable tertiary amines include trimethyl amine.triethylamine. dimethylethanolamine. N N,N',-N-tetramethyl-1.3-butanediamine. N.N-dimethylcyclohexylamine,N,N-dimethylbenzylamine. N N-dimethylphenylethylamine,Nmethylpyrrolidine N- methylmorpholine. N-ethylmorpholine, N-methylpiperidine. N,N-dimethylpiperazine and L4- diazabicyclo [2.2.2]octane. Organic metal compounds which may be used as catalysts includedibutyltin dilaurate and stannous octoate. It is often advantageous touse a catalyst combination of a tertiary amine and a tin compound, forexample l.4-dia7.abicyclo[2.2.2] octane and dibutyltin dilaurate.

Surface active agents which may be used in the process of the inventionhave been fully described in the prior art relating to polyurethanes andinclude siloxane-oxyalkylene copolymers and ethylene oxide/propyleneoxide block copolymers.

Component (h) should be a mobile liquid which mixes readily withcomponent (a). The two components may be mixed together in anyconvenient manner using. for example. mixing means already described inthe prior art.

The process of the invention is particularly suitable for thepreparation of cellular polyurethane elastomers having densities in therange 0.1 l.0 g/cc. Such mate rials are useful as soles for shoes andmay advantageously be prepared by the reaction of (u) a prepolymerderived from substantially pure 4.4- diphenylmethane diisocyanate and alinear or slightly branched polyester polyol having a hydroxyl numberwithin the range 30 to 120 with (h) a pre-formed mixture containing apolyoxypropylene or poly(oxyethylcne-oxypropylene) diol or triol havinga hydroxyl num' ber within the range 25 l 12. a glycol chain-extender.one or more catalysts. a surface active agent and sufficient blowingagent to give a product of the desired density under the foamingconditions being used.

it is often advantageous to prepare the aforesaid cellular polyurethaneclastomers by foaming components (a) and (h) in a closed mould having avolume less than that which would be occupied by the resultant foam ifthe reaction mixture were allowed to rise freely. Such overpackingtechniques have been fully described in the prior art. The desiredamount of reaction mixture is introduced into a mould which is thenclosed. A suitable degree of overpacking may be achieved by introducinginto the mould an amount of reaction mixture which. if allowed to risefreely, would produce a foam having a volume at least l.l times thevolume of the mould. Preferably, the amount of reaction mixture shouldbe such that, if allowed to rise freely, would produce a foam having avolume from 1.5 to 10 times the volume of the mould. For the productionof shoe soles, the foam-forming components are introduced into mouldscorresponding in size and shape with the de sired products. For thispurpose, products having densities in the range 0.5 0.7 g/cc are mostsuitable.

The process of the invention has the advantage of greater ease ofhandling and processing compared with processes based wholly onpolyesters. This is because polyesters in general. are solids or slowlycrystallising viscous liquids whereas polyethers, in general. areliquids of lower viscosity.

The invention is illustrated but not limited by the following Examplesin which all parts and percentages are by weight.

EXAMPLE 1 A prepolymer having an NCO content of l8.l7( is prepared byreacting 61.3 parts of 4,4-

diphenylmethane diisocyanate with 42.9 parts of poly(ethylene/propyleneadipate) for 2 hours at 80C. The poly(ethylene/propylene adipate) has ahydroxyl value of 56 mg KoH/g, an acid value less than 2 mg KoH/g and isprepared by reacting 467 parts of adipic acid with 154 parts of ethyleneglycol and 8l parts of propylene glycol.

104.2 Parts of the prepolymer are mixed with 87.| parts of a pre-formedblend consisting of:

1oly(oxycthylene-oxypropylene)triol 70.0 parts lA-hutanediol I53 parts l-&-dia'/abicyclo| 2.2.2loctane (I 2 part dibutyltin dilaurate (I 1 partsiloxane-oxyalkylene copolymer 1.0 part (Silicone [.5340) water 0.5party The poly(oxyethylene-oxypropylene) triol is made by reactingglycerol with propylene oxide to form a polyoxypropylene triol which isthen reacted with ethylene oxide. The final product has an oxyethylenecontent of i371, a hydroxyl value of 32 mg KoH/g and 7571 of thehydroxyl groups are primary hydroxyls.

The cellular polyurethane product has a density of 0.4 g/cc (free rise).

Silicone L5340 is a clear liquid silicone surfactant sold for rigidurethane foam systems having a specific gravity of L053 at 25C and aviscosity at 25C of l.000 centistokes.

EXAMPLE 2 A prepolymer having an NCO content of 16.19? is prepared byreacting I03 parts of 4.4-

diphenylmethane diisocyanate with 87.l parts of poly- (ethylenetetramethylene adipate) for 2 hours at 80C. The poly(ethylenetetramethylene adipate) has a hydroxyl value of 56.0 mg KOH g". an acidvalue less than 2.0 mg KOH g and is prepared by reacting 823 parts ofadipic acid with 205 parts of ethylene glycol and 292 parts of l4-butane diol.

l00 parts of the prepolymer at 40C are mixed with 65 parts of a blend at22C preformed from:

polyl oxyethylenc-oxy propylene )triol 4)h.l parts (as described inExample I l.-l--butane diol UNA) parts l.4-dia7ahic \clo| 2.2.2 loctauc1.7 parts dihutyltiu dilaurale 0.8 part siloxanemxyalkylcne eopolymer(Silicone Pk L53-l0) water 4.0 parts.

The cellular polyurethane product has the charcteristics given in theTable below.

EXAMPLE 3 A prepolymer having an NCO content of 17.8% is prepared byreacting l03 parts of 4.4-

diphenylmethane diisocyanate with 70.3 parts of poly- (ethylenetetramethylene adipate) for 2 hours at 80C. The poly(ethylenetetramethylene adipate) is as described in Example 2.

l parts of the prepolymer at 40C are mixed with 91.8 parts of a blend at22C preformed from:

poly(ox cthylcnc-oxypropylenc)triol 339.3 parts [as described in ExampleI l Pluronic 1.44 (Wyandotte Chemicals) 339.3 parts l.-l-hutanc diollnL-l parts l.-l-diazabicyclol 2.2.2 loctane l .9 parts dibutyltindilaurate 0.9 part siloxanc-oxyalkylenc copolymer 9.4 parts (Silicone[.5340] water 2.0 parts Trichlorofluoromcthanc r4.| parts EXAMPLE 4 95parts of the prepolymer described in Example 3 at 40C are mixed with 85parts of a blend at 22C preformed from:

polyl oxyethylcnc-oty propy lene )triol 4h0.l parts Pluronic 1. 2(Wyandoltc Chemicals) 230.l parts l.-l-bulanc diol I505) partsl.-l-dia/.'rhic \clo| 2.2.2 loctanc I. parts dibutyltin dilauratc 0.9part Siloxanc-oxyalkylcne copolymcr (silicone 9.3 parts [53-80) water4.0 parts.

The poly( oxyethylcne-oxypropylene triol is made by reacting glycerolwith propylene oxide to form a poly oxypropylene triol which is thenreacted with ethylene oxide. The final product has an oxyethylcnecontent of a hydroxyl value of 32 mg KOH g and 80% of the hydroxylgroups are primary hydroxyls.

The Pluronic L72 (Wyandotte Chemicals) is an oxyethylated polypropyleneglycol which has a hydroxyl value of mg KOH g a polypropylene glycolmolecular weight of 2050 and a polyoxyethylene content of 207:.

The cellular polyurethane product has the characteristics given in theTable below.

EXAMPLE 5 A prepolymer having an NCO content of 18.0% is prepared byreacting 103 parts of 4.4-

diphenylmethane diisocyanate with 70.3 parts of poly( diethyleneadipate) for 2 hours at 80C. The poly(- diethylene adipate) has ahydroxyl value of 56.0 mg KOH g". an acid value less than 2.0 mg KOH gand is prepared by reacting 438 parts of adipic acid with 358 parts ofdiethylene glycol.

95 parts ol'the prepolymer at 40C are mixed with 85 parts of the blenddescribed in Example 4 at 22C.

The cellular polyurethane product has the character istics given in theTable below.

EXAMPLE 6 A prepolymer having an NCO content of l9.97c is prepared byreacting 103 parts of 4.4- 5 diphenylmethane diisocyanate with 56.2parts of poly( diethylene adipate) for 2 hours at 80C. The poly(-diethylene adipate) is as described in Example 5.

84.6 parts of the prepolymer at 40C are mixed with 95.4 parts of a blendat 22C pre-formed from:

poly( oxycthylene-oxypropylene ltriol 592 5 parts (as described inExample 4) Pluronic-L72 (Wyandottc Chemicals) 296.3 parts 1.4-butanediol1784 parts l.4-dia7.abicyclo[ 2.2.2 loctane 2.] parts dibulyltindilaurate l.0 part siloxane-oxyalkylene copolymcr (Silicone l0.5 parts1.5340) water 2 3 parts trichlorofluoromethanc 70.) parts.

The cellular polyurethane product has the characteristics given in theTable below.

EXAMPLE 7 86.5 parts of the prepolymer described in Example 6 at 40C aremixed with 93.5 parts ofa resin at 22C preformed from:

Pluronic L44 (Wyandotte Chemicals) 838.] parts 3t) l.4-hutane diol 1553parts l ,J-diazabicyclol 2.2.2 [octane l.2 parts dibutyl tin dilauratc0h part water 5.0 parts silownc-oxyalkylene copolymer l0.l partslSiliconc [.53-80) The cellular polyurethane product has thecharacteristics given in the Table below.

EXAMPLE 8 A prepolymer having an NCO content of I967: is prepared byreacting 103 parts of 4,4- diphenylmethane diisocyanate with 58.8 partsof poly- (ethylene adipate) for 2 hours at 80C. The poly(ethyleneadipate) has a hydroxyl value of 56.0 mg. KOH g. an acid value less than2.0 mg KOH g and is prepared by reacting 835 parts of adipic acid with390 parts of ethylene glycol.

86.5 parts of the prepolymer at C are mixed with 93.5 parts of the resinblend described in Example 7.

The cellular polyurethane product has the characteristics given in theTable below.

EXAMPLE 9 90.l parts of the prepolymer described in Example 8 at 40C aremixed with 89.9 parts ofa resin at 22C performed from:

Pluronic L64 (W'yandottc Chemicals) 388.8 parts 6poly(oxyethylcne-oxyprop lcne)triol (as 388.8 parts described in Example4| lA-hutane diol H112 parts lAxHazabicyclol 2.2.2 loctanc 20 partsdihutyl tin dilauratc l1) parts water 5.0 parts silrixanwoxyalkyleuccopolymer 9.8 parts. 6 Silicone 1.5340) The Pluronic L64 is anoxyethylated polypropylene glycol which has a hydroxyl value of 38.7 mgKOH/g a polypropylene glycol molecular weight ol- I750 and apolyoxyethylene content of 40%.

The cellular polyurethane product has the characteristics given in theTable below.

EXAMPLE l() polyethylene adipatel 120.5 parts Isl-butane diol I50 4parts l.-l-diazahic clol 2.2.1 |octane 711 parts siloxane-oxyalkylenecopolymcr 1 I111 parts {Silicone l.53-HI| water 1.5 parts.

The poly(ethylene adipate) is as used in the preparation of theprepolymer.

The cellular polyurethane product has the characteristics given in theTable below.

ltl

components into a mould having a volume that is approximately hallthefree rise volume of the reaction mixture.

We claim:

1. A process for the manufacture of cellular polyurethanes whichcomprises intimately mixing:

a. a prepolymer having an NCO content of lS-ZV/r by weight prepared bythe reaction of a polyester polyol having from two to four hydroxylgroups per molecule and a hydroxyl number of from 50 to 60 with anexcess of diphenylmethane diisocyanate. and b a mixture containing apolyoxypropylene or poly( tixypropylene-oxyethylene )polyol having fromtwo to four hydroxyl groups per molecule and a hydrosyl number of from30 to 60. 18.5 to 28%. based on the weight of said mixture of L4-butanediol. a blowing agent. a catalyst and a surface active agent. theratio of isocyanate groups in component (a) to active hydrogen atoms incomponent (b) being substantially within the range of 0.95:] to 12:1.introducing into a closed mold a quantity of the resultant mixturesul'licient to produce a cellular polyurethane whose TABLE PHYSICALCHARACTERISTICS OF FOAMS PREPARED IN EXAMPLES 2-10 The fifth column ofthe Table gives the density of foams made under free rise conditions.The sixth and seventh columns give the properties of cellularelastomeric sheets obtained by introducing the foam-forming volume is atleast l.l times the volume of the mold if said quantity were allowed toreact and rise freely. and

foaming said mixture in said close: mold.

1. A PROCESS FOR THE MANUFACTURE OF CELLULAR POLYURETHANES WHICHCOMPRISES INTIMATELY MIXING: A. A PREPOLYMER HAVING AN NCO CONTENT OF15-21% BY WEIGHT PREPARED BY THE REACTION OF A POLYESTER POLYOL HAVINGFROM THE TWO TO FOUR HYDROXYL GROUPS PER MOLECULE AND A HYDROXYL NUMBEROF FROM 50 TO 60 WITH AN EXCESS OF DIPHENYLMETHANE DIISOCYANATE, AND B.A MIXTURE CONTAINING A POLYOXYPROPYLENE ORPOLY(OXYPROPYLENE-OXYETHYLENE)POLYOL HAVING FROM TWO TO FOUR HYDROXYLGROUPS PER MOLECULE AND A HYDROXYL NUMBER OF FROM 30 TO 60, 18.5 TO 28%,BASED ON THE WEIGHT OF SAID MIXTURE OF 1,4-BUTANEDIOL, A BLOWING AGENT,A CATALYST AND A SURFACE ACTIVE AGENT, THE RATIO OF ISOCYANATE GROUPS INCOMPONENT (A) TO ACTIVE HYDROGEN ATOMS IN COMPONENT (B) BEINGSUBSTANTIALLY WITHIN THE RANGE OF 0.95:1 TO 1.2:1, INTRODUCING INTO ACLOSED MOLD A QUANTITY OF THE RESULTANT MIXTURE SUFFICIENT TO PRODUCE ACELLULAR POLYURETHANE WHOSE VOLUME IS AT LEAST 1.1 TIMES THE VOLUME OFTHE MOLD IF SAID QUANITY WERE ALLOWED TO REACT AND RISE FREELY, ANDFOAMING SAID MIXTURE IN SAID CLOSED MOLD.